Larisa Brass: Local firm partners with lab to solve solar riddle

In the race to make more efficient, cheaper solar technology, a Jefferson City company is closing in on a solution one of its founders says could revolutionize the way photovoltaics are made.

Mossey Creek Enterprises is one of four companies working under a cooperative research agreement with Oak Ridge National Laboratory to develop new and improved solar technology. The company has received about $380,000 in federal dollars to research and develop a technique that will decrease the energy and material used to make the silicon wafers used in solar cells — and not just by a smidge, says John Carberry, who owns the firm with his son Matthew Carberry and partner Bruce Charles.

"We believe we can reduce (the cost of solar) from 70 cents to 15 cents a watt," he says.

Currently, just 15 percent to 30 percent of the material used to make silicon wafers ends up as viable product. The process consumes large amounts of energy and the silicon coming out the other end of the process contains impurities that impact its overall efficiency in photovoltaic panels, he says.

Over the past two years, Mossey Creek has been working on these problems, using ORNL's High Temperature Materials Laboratory to test concepts Carberry has been mulling since he left his position as CEO of Michigan-based Silbond, which produced a precursor to silicon for the semiconductor industry. Carberry has been in Jefferson City since 1996, when he founded the fiber-optics company Neptec, and since then has launched a variety of technology-based firms. But he's been quietly developing, and largely self-funding, the silicon-production technology over the past 15 years.

In the silicon industry's early days of development, Carberry says, "I publicly said this technology was so inefficient that somebody had to come along with a better idea. Nobody did it."

The pressure to make solar technology cost competitive with existing power generation is driving the push toward better processes, making the startup's efforts a self-fulfilling prophecy.

The new production process has three facets, he says.

First, the company has a developed a way to make silicon powder that is fine but very pure. Second, an ability to rapidly heat and cool tools used to melt and shape the silicon helps to exponentially trim energy costs by doing away with the current process of forming large ingots using crucibles heated to high temperatures for long periods of time. These then must be cleaned and cut in preparation for processing into wafers.

The new technique produces one wafer at a time, increasing overall yield to 95 percent and eliminating the need to meld the material in bulk, Carberry says. The final innovation is a special coating for the graphite tools used in wafer production that prevents reactions with the silicon that can further compromise quality of the product.

"It takes five seconds instead of 56 hours," he says, with the final product a net-shaped wafer 156 millimeters square and 150 microns thick. "The wafer is ready to go."

Proven in the lab, within three to six months the technology should be ready for larger-scale production, and the company is seeking $3 million to $6 million in capital investment to fund a small, commercial-grade, beta test facility. The plant's capacity would be 50 to 100 megawatts, producing "something like 12 million wafers," he says.

"The intention is to build it out somewhere along Pellissippi Parkway, so we stay close to the collaborators of the lab," he says.

Mossey Creek is already in talks with companies about licensing the technology for their production facilities, something Carberry sees as an attractive proposition for solar firms locating in Tennessee.

This year's demand will total an estimated 5 billion silicon wafers, he says, and the industry will spend $6.5 billion on production equipment to meet the demand. "If ORNL and (Mossey Creek Enterprises) are able to successfully introduce this technology as a locally controlled technology, Tennessee could benefit from a high-tech, home-based business able to create many thousands of high-tech, well-paying jobs," he says.

Solar isn't Mossey Creek's only foray into the energy market.

The company is also working with ORNL to develop heat transfer materials and systems to remove heat generated by devices, including inverters and film capacitors used in electric and hybrid cars as well as motors and semiconductors, in order to improve their efficiency and life expectancy.

The firm is also developing thermo-electric technology to help channel the up to 70 percent of heat generated and wasted by power plants, large factories and refineries into usable energy.

"The U.S. will use 100 quads of energy this year … and 60 percent of that is waste heat," he says. "Half of that, or 30 percent of the total, is industrial waste heat."

The early work has been promising, Carberry says, and promises to make much greater impact than the solar technology.

"If you recover 20 percent of the waste heat, that's 12 quads and that's way more than solar can ever (produce)," he says, adding "We're still at the proof-of-principle stage. It will take a year or two years to move this forward."

Larisa Brass is a contributing writer to the Greater Knoxville Business Journal. She can be reached at news@knoxvillebiz.com.